Ozempic Weight Regain May Leave 25 Percent of Weight Loss After One Year

New analysis indicates that people who stop using Ozempic-like medicines retain roughly 25 percent of the weight they lost for as long as a year afterwards. The important uncertainty, however, is whether that retained loss comes from fat or muscle.

Ozempic-like drugs and unanswered questions about muscle loss

This unresolved clinical question draws attention to a little-studied effect of semaglutide, tirzepatide and other medicines used to treat type 2 diabetes or manage body weight. Early research suggests that lean muscle mass could account for 40 to 60 percent of the weight lost while on treatment.

Although it is well established that people put weight back on once they discontinue these medicines, researchers do not yet know what that regained weight consists of.

"If the regained weight is disproportionately fat, individuals may ultimately be worse off than before in their fat-to-lean mass ratio, which may have adverse consequences for their health," explains medical researcher Brajan Budini, co-first author of the study from a University of Cambridge team in the UK.

The team’s published paper offers a broad review of evidence on weight gain after treatment ends. It is also the first to model the pattern of this weight regain for up to 52 weeks following cessation.

Managing weight after treatment is significant because more than a billion people around the world live with obesity. GLP-1 medicines have shown substantial effectiveness, with some people achieving reductions of 20 percent or more in body weight.

These drugs replicate the effects of glucagon-like peptide-1 (GLP-1), a naturally occurring hormone that helps regulate blood sugar and suppress appetite. However, gastrointestinal side effects, other adverse effects, high costs and prescription barriers mean that around half of patients stop taking GLP-1 medicines during their first year.

"Drugs such as Ozempic and Wegovy act like brakes on our appetite, making us feel full sooner, which means we eat less and therefore lose weight," says Budini.

"When people stop taking them, they are essentially taking their foot off the brake, and this can lead to rapid weight regain."

Evidence on weight regain after GLP-1 treatment

To estimate how much weight patients regain after ending treatment, the researchers assessed 48 relevant studies. They quickly identified notable limitations and inconsistencies.

Several studies monitored patients’ weight for only a few weeks, while the timing of follow-up appointments after medication cessation differed considerably between studies. In general, the authors note that post-GLP-1 weight gain "has been largely underexplored in the literature."

The researchers therefore selected only a small number of high-quality publications that fulfilled specified requirements. Studies needed to be randomised, enrol more than 100 people each, report weight loss of at least 3 kilograms (6.6 pounds), and include at least one follow-up 12 weeks after the medicine was stopped.

Their systematic review was consequently narrowed to six randomised controlled trials (RCTs), involving more than 3,200 participants. These particularly robust trials tracked people for as long as 52 weeks after they stopped taking weight-loss medicines.

This relatively small meta-analysis found that former GLP-1 users regained weight quickly at first, before the rate of gain progressively slowed. By one year after stopping the drugs, participants had regained 60 percent of the weight lost during treatment.

Using those findings, the team also modelled outcomes beyond 52 weeks. Their projections suggest weight regain starts to level off at 60 weeks, declining after patients have regained 75 percent of the weight they lost while receiving treatment. The reason remains unclear.

Semaglutide, tirzepatide and preserving lean mass

One possibility is that these medicines enable people to develop healthier dietary habits or trigger physiological effects, including changes to hormone levels or hypothalamic function.

Yet muscle makes up a substantial share of the weight lost, and it is unknown whether lean mass returns as rapidly as fat mass once treatment finishes. In addition, newer and more potent medicines, including semaglutide and tirzepatide, are less successful at maintaining lean mass - meaning they can produce greater overall weight loss irrespective of where that loss comes from.

Prescription approaches involving gradual dose reductions might therefore help patients maintain fat loss, at least. Doctors can also support patients by encouraging healthy eating and exercise, both of which are essential to lasting wellbeing.

"It's important that people are given advice on improving their diet and exercise, rather than relying solely on the drugs, as this may help them maintain good habits when they stop taking them," concludes medical researcher and co-first author Steven Luo.

The research was published in eClinicalMedicine.